linux-kernel - Re: [RFC PATCH 1/7] riscv: Get rid of compile time logic with MAX_EARLY_MAPPING

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Date:   Thu, 26 Mar 2020 11:40:56 +0530
From:   Anup Patel <anup@...infault.org>
To:     Alexandre Ghiti <alex@...ti.fr>
Cc:     Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Zong Li <zong.li@...ive.com>, Christoph Hellwig <hch@....de>,
        linux-riscv <linux-riscv@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org List" <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH 1/7] riscv: Get rid of compile time logic with MAX_EARLY_MAPPING_SIZE

On Sun, Mar 22, 2020 at 4:31 PM Alexandre Ghiti <alex@...ti.fr> wrote:
>
> There is no need to compare at compile time MAX_EARLY_MAPPING_SIZE value
> with PGDIR_SIZE since MAX_EARLY_MAPPING_SIZE is set to 128MB which is less
> than PGDIR_SIZE that is equal to 1GB: that allows to simplify early_pmd
> definition.
>
> Signed-off-by: Alexandre Ghiti <alex@...ti.fr>
> ---
>  arch/riscv/mm/init.c | 16 ++++------------
>  1 file changed, 4 insertions(+), 12 deletions(-)
>
> diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
> index 238bd0033c3f..18bbb426848e 100644
> --- a/arch/riscv/mm/init.c
> +++ b/arch/riscv/mm/init.c
> @@ -247,13 +247,7 @@ static void __init create_pte_mapping(pte_t *ptep,
>
>  pmd_t trampoline_pmd[PTRS_PER_PMD] __page_aligned_bss;
>  pmd_t fixmap_pmd[PTRS_PER_PMD] __page_aligned_bss;
> -
> -#if MAX_EARLY_MAPPING_SIZE < PGDIR_SIZE
> -#define NUM_EARLY_PMDS         1UL
> -#else
> -#define NUM_EARLY_PMDS         (1UL + MAX_EARLY_MAPPING_SIZE / PGDIR_SIZE)
> -#endif
> -pmd_t early_pmd[PTRS_PER_PMD * NUM_EARLY_PMDS] __initdata __aligned(PAGE_SIZE);
> +pmd_t early_pmd[PTRS_PER_PMD] __initdata __aligned(PAGE_SIZE);
>
>  static pmd_t *__init get_pmd_virt(phys_addr_t pa)
>  {
> @@ -267,14 +261,12 @@ static pmd_t *__init get_pmd_virt(phys_addr_t pa)
>
>  static phys_addr_t __init alloc_pmd(uintptr_t va)
>  {
> -       uintptr_t pmd_num;
> -
>         if (mmu_enabled)
>                 return memblock_phys_alloc(PAGE_SIZE, PAGE_SIZE);
>
> -       pmd_num = (va - PAGE_OFFSET) >> PGDIR_SHIFT;
> -       BUG_ON(pmd_num >= NUM_EARLY_PMDS);
> -       return (uintptr_t)&early_pmd[pmd_num * PTRS_PER_PMD];
> +       BUG_ON((va - PAGE_OFFSET) >> PGDIR_SHIFT);
> +
> +       return (uintptr_t)early_pmd;
>  }
>
>  static void __init create_pmd_mapping(pmd_t *pmdp,
> --
> 2.20.1
>

Looks good to me.

Reviewed-by: Anup Patel <anup@...infault.org>

Regards,
Anup